Answers

2016-07-10T15:43:28+08:00
Sn=530 a10=80 a1=? D=? Sn=n(a1+an)/2 [530=10(a1+80)/2] 1060=10a1+800 1060-800=10a1 260/10 = 10a1/10 26=a1 An=a1+(n+1)d 80=26+(10-1)d 80=26+9d 80-26=9d 54/9=9d/9 6=d
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